Fluidization chambers for processing materials comprise at the base a device for distributing a gaseous fluid throughout the section of the chamber and for producing a fluidization of a particulate material fed to said chamber.
In the field of industrial fluidized beds for processing materials, it is known to employ as the fluidization device planar plates which are perforated so as to constitute an even network and which are provided with pipes surmounted by a mushroom-shaped cap or with thick pipes provided with radial apertures. This system has the advantage of being protected against the introduction of solid particles in the main gaseous fluid supply conduit. On the other hand, this structure in which the plate must resist large thermal and mechanical loads by its rigidity as concerns bending and in which multiple mushroom caps must be constructed, results in high constructional costs.
It is also known to employ as a device for producing a fluidization planar plates which are perforated and provided with venturi. But in order to be protected against introduction of solid particles in the supply conduits, a fluidization agent introducing siphon or trap must be provided. It is then necessary to carry out a regular inspection to ascertain whether the venturi is or is not blocked by particles, and this requires an individual supply of fluidization agent to each venturi. This mode of construction therefore results in a modification of equilibrating, insulating and deblocking means which results in large pressure drops.
Further, these devices as operate either in a dense bed or a circulating bed and they do not permit passing from one field of fluidization to the other with the same apparatus. For this purpose, a device is known for producing fluidization which is formed by a grid including a first assembly of passageways connected to a gaseous fluid supply system and a second assembly of complementary passageways connected to another gaseous fluid supply system. The two assemblies are supplied separately or simultaneously, depending on the desired mode of fluidization. This double arrangement consequently multiplies the inspection and control means, and increases the production costs.